It has become well established that there are major health benefits from regular endoscopic examinations of a patient's internal structures such as the alimentary canals and airways, e.g., the esophagus, stomach, lungs, colon, uterus, urethra, kidney, and other organ systems. Endoscopes are also commonly used to perform surgical, therapeutic, diagnostic or other medical procedures under direct visualization. A conventional imaging endoscope used for such procedures generally include an illuminating mechanism such as a fiber optic light guide connected to a proximal source of light, and an imaging means such as an imaging light guide to carry an image to a remote camera or eye piece or a miniature video camera within the endoscope itself. In addition, most endoscopes include one or more working channels through which medical devices such as biopsy forceps, snares, fulguration probes and other tools may be passed in order to perform a procedure at a desired location in the patient's body.
In connection with the endoscope, an operator control module is typically provided that allows a user to control and steer the operation of the endoscope. The endoscope is guided through the patient's tract or canal until an opening at the distal end of the endoscope is proximate to the area of the patient's body which is to be examined or receive treatment. At this point, the endoscope allows other components, such as a catheter, to access the targeted area.
In many endoscope procedures, the physician or operator needs to rotate an endoscope shaft in order to obtain the desired images, to obtain a desired position of the distal tip, or to perform a desired surgical function (e.g. polyp removal, drainage, and the like). An endoscope shaft with low torque transfer characteristic allows for shaft rotation by allowing the shaft to twist around its central axis; however, excessive rotation of the shaft can damage the cables, tubes and electrical wires within the shaft. On the other hand, an endoscope shaft that is not allowed to rotate at all may loop over itself during clinical use, causing damage to the internal components as well as discomfort to the patient.